There is a recognized need for specific and reliable information regarding the dose/response relationships between physical activity and health for all segments of the population. New methods for assessing physical activity and energy expenditure (EE) in free-living populations are needed before a systematic evaluation and interpretation of these dose-response relationships between physical activity and specific health-related results can be undertaken. Our objective is to demonstrate the feasibility of a low-cost, unobtrusive acceleration pattern acquisition and analysis system. This instrument will identify and quantify the physical activities that generate these patterns. At the end of this program, we will provide an intelligent system that is practical from both a cost and unobtrusive use prospective, thus making it an instrument of choice for epidemiologic physical activity studies of large free-living populations. [unreadable] [unreadable] [unreadable]